This thesis reports on three empirical studies that focus on questions concerning knowledge sharing and construction in communities of practice and global knowledge exchange platforms. The first essay presents an exploratory case study on a particular academic community of practice--AISNET and its central knowledge exchange platform, the ISWorld Mailing List--over a four-year period from 2002 to 2006. Using content analysis of archival data, the study not only finds that this particular case of knowledge platform offers a highly efficient communication tool for knowledge dissemination to the IS community but also that its usage has been shifting strongly towards information broadcasting and away from interactive knowledge exchange and creation. The second study investigates the major drivers of internationalization of online communities of practice. A research model is presented, that extends conventional approaches based on differences in economic and technological infrastructure. The model also incorporates language proficiency and cultural differences as additional major factors that determine active user participation. Using panel data across six years (from 2002 to 2008), I examined the antecedents of digital inequality on AISNET knowledge platform. The results of the study confirmed previous digital divide research that found that economic and technological conditions are positively associated with the active usage of global online resources. The third study further extends the research model developed for study 2. In this model, the multi-language options of knowledge platforms are proposed to mitigate the effects of language and socio-cultural barriers. In the test model, other platform features such as platform type ("brick-and-click vs. pure click") and platform focal country ("United States vs. Non United States") are included as antecedents. Using a data set comprising of two-hundred leading online knowledge exchange platforms, the test results regarding national factors are consistent with all of the hypotheses proposed except for the effect of technological readiness, which shows significant negative effects. In terms of platform features, availability of a multi-language option shows significant moderating effects on language barriers but not on cultural distance. The thesis concludes with a discussion of the linkages across the three studies and the key contributions of my research, and some suggestions for possible future research. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]